Hopefully the first two videos have sufficiently impressed you with the power of masks. If not, this video about editing masks with the brush tool absolutely will. By this point you've seen the power of masks, but haven't seen how they relate to a painting process. Once you begin adding nuance and painterly edges to your mask with the brush tool, you'll see what you've been missing all this time. It can be hard to explain in words, but all experienced digital painters will agree that masks bring unique power to the painting process.